Systems and methods for low-manganese welding wire

ABSTRACT

The invention relates generally to welding and, more specifically, to welding wires for arc welding, such as Gas Metal Arc Welding (GMAW) or Flux Core Arc Welding (FCAW). In one embodiment, a tubular welding wire includes a sheath and a core. The tubular welding wire includes less than approximately 0.4% manganese metal or alloy by weight, and the tubular welding wire is configured to form a weld deposit having less than approximately 0.5% manganese by weight.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority from and the benefit of U.S.Provisional Application Ser. No. 61/651,279, entitled “SYSTEMS ANDMETHODS FOR LOW-MANGANESE WELDING WIRE,” filed May 24, 2012, which ishereby incorporated by reference in its entirety for all purposes.

BACKGROUND

The invention relates generally to welding and, more specifically, toelectrodes for arc welding, such as Gas Metal Arc Welding (GMAW) or FluxCore Arc Welding (FCAW).

Welding is a process that has become ubiquitous in various industriesfor a variety of applications. For example, welding is often used inapplications such as shipbuilding, offshore platform, construction, pipemills, and so forth. Certain welding techniques (e.g., Gas Metal ArcWelding (GMAW), Gas-shielded Flux Core Arc Welding (FCAW-G),Self-shielded Flux Core Arc Welding (FCAW-S), and Submerged Arc Welding(SAW)), typically employ a welding electrode in the form of weldingwire. Welding wire may generally provide a supply of filler metal forthe weld as well as provide a path for the current during the weldingprocess.

BRIEF DESCRIPTION

In an embodiment, a tubular welding wire includes a sheath and a core.The tubular welding wire includes less than approximately 0.4% manganesemetal or alloy by weight, and the tubular welding wire is configured toform a weld deposit having less than approximately 0.5% manganese byweight.

In another embodiment, a method includes forming a weld deposit on aworkpiece using a welding electrode, in which the weld deposit comprisesless than approximately 0.5% manganese by weight. Further, a CharpyV-Notch (CVN) toughness of the weld deposit is greater thanapproximately 65 foot-pounds (ft-lbs) at −20° F. and greater thanapproximately 45 ft-lbs at −40° F.

In another embodiment, a method of manufacturing a welding electrodeincludes forming an agglomerate by sintering a mixture comprisingpigment-grade titanium dioxide, potassium silicate, sodium silicate, andlithium fluoride. The method also includes mixing the agglomerate withat least one alloying component, at least one arc stabilizing component,and at least one deoxidizing component to form a granular core. Themethod further includes disposing the granular core within a metallicsheath to form the welding electrode, wherein the welding electrodecomprises less than approximately 0.4% manganese metal or alloy byweight.

DRAWINGS

These and other features, aspects, and advantages of the presentinvention will become better understood when the following detaileddescription is read with reference to the accompanying drawings in whichlike characters represent like parts throughout the drawings, wherein:

FIG. 1 is a block diagram of a gas metal arc welding (GMAW) system, inaccordance with embodiments of the present disclosure;

FIG. 2 is a cross-sectional view of a tubular welding wire, inaccordance with embodiments of the present disclosure;

FIG. 3 is a process by which the tubular welding wire may be used toweld a workpiece, in accordance with embodiments of the presentdisclosure; and

FIG. 4 is a process for manufacturing the tubular welding wire, inaccordance with embodiments of the present disclosure.

DETAILED DESCRIPTION

One or more specific embodiments of the present disclosure will bedescribed below. In an effort to provide a concise description of theseembodiments, all features of an actual implementation may not bedescribed in the specification. It should be appreciated that in thedevelopment of any such actual implementation, as in any engineering ordesign project, numerous implementation-specific decisions must be madeto achieve the developers' specific goals, such as compliance withsystem-related and business-related constraints, which may vary from oneimplementation to another. Moreover, it should be appreciated that sucha development effort might be complex and time consuming, but wouldnevertheless be a routine undertaking of design, fabrication, andmanufacture for those of ordinary skill having the benefit of thisdisclosure.

When introducing elements of various embodiments of the presentdisclosure, the articles “a,” “an,” “the,” and “said” are intended tomean that there are one or more of the elements. The terms “comprising,”“including,” and “having” are intended to be inclusive and mean thatthere may be additional elements other than the listed elements. Itshould be appreciated that, as used herein, the term “tubular weldingelectrode” or “tubular welding wire” may refer to any welding wire orelectrode having a metal sheath and a granular or powdered core, such asmetal-cored or flux-cored welding electrodes. It should be appreciatedthat the term “tubular,” as used herein, may include various shapes ofwelding wire, including round, elliptical, square, polygonal, or anyother suitable shape.

Certain types of welding wire (e.g., tubular welding wire) may includeone or more components (e.g., flux, arc stabilizers, or other additives)that may generally alter the welding process and/or the properties ofthe resulting weld. For example, rutile is a mineral, primarily composedof titanium dioxide (TiO₂), which may also include compounds of iron(Fe), niobium (Nb), tantalum (Ta), vanadium (V), and/or otherimpurities. Furthermore, rutile may be included in some types of weldingwires, such as T-1 welding wires (e.g., AWS A5.20 EXXT-1, A5.29EXXT1-YY, A5.36 EXXT-1, and EXXT1-YY). By further example, certain typesof welding wires may include a substantial quantity of manganese (Mn)(e.g., greater than 0.5% by weight) to function as a deoxidizer and/oran alloying metal for the resulting weld. That is, this manganesecontent may react with oxygen near the welding environment to formoxides of manganese (e.g., manganese oxide (MnO) and/or manganesedioxide (MnO₂)) that flow into the slag and/or transfer into the weldpool becoming incorporated into the weld metal to improve the mechanicalproperties of the resulting weld. In general, manganese may form alloyswith certain metals (e.g., steel) to provide improved strength,ductility, and toughness. In certain environments, the manganese may actas a deoxidizer reacting with oxygen (e.g., from the atmosphere) inorder to block (e.g., limit or prevent) this oxygen from remaining inthe weld deposit. Similarly, manganese may react with and remove sulfurfrom the welding environment. Furthermore, manganese in a welding wiremay help to control the weld puddle (e.g., by improving the wetting ofthe workpiece).

However, despite these effects, it may be desirable, in certainsituations, to utilize a low-manganese welding wire. For example, awelding wire having low manganese content (e.g., less than 0.5%, lessthan 0.35%, or less than 0.26% manganese by weight) may volatilize onlya small quantity of manganese during the welding operation. Accordingly,the present disclosure is directed toward systems and methods forwelding wires having low manganese content that may be used to producewelds having a low manganese content (e.g., less than approximately0.5%, less than approximately 0.4%, or less than 0.3% manganese byweight) while still providing suitable weld properties (e.g., tensilestrength, ductility, toughness, and so forth). In other words, thepresently disclosed welding wires generally maintain the weld quality(e.g., a weld having a reasonable level of inclusions, good strength,and/or good toughness) despite the low manganese content.

In certain embodiments, the disclosed welding wires achieve theaforementioned welding properties and weld quality despite the lowmanganese content, at least in part, through the use of a purified,agglomerated titanium dioxide component. For example, the granular coreof certain presently disclosed tubular welding wire embodiments mayinclude pigment-grade TiO₂ that has been agglomerated with bindingand/or drying agents (e.g., sodium silicate, potassium silicate, lithiumfluoride, and/or other binding or drying agents). Furthermore, certainembodiments of the presently disclosed welding wire may include highlevels of deoxidizers (e.g., zirconium, aluminum, magnesium, silicon,and/or other suitable deoxidizers) to generally deter (e.g., block)oxygen incorporation into the weld metal. Accordingly, as set forthbelow, the presently disclosed tubular welding wires enable theformation of weld deposits having relatively low manganese content(e.g., generally less than approximately 0.5% by weight) while stillaffording good weld properties (e.g., tensile strength, ductility,toughness, and so forth).

Turning to the figures, FIG. 1 illustrates an embodiment of a gas metalarc welding (GMAW) system 10 that utilizes tubular welding wire, inaccordance with the present disclosure. It should be appreciated that,while the present discussion may focus specifically on the GMAW system10 illustrated in FIG. 1, the presently disclosed welding wire maybenefit a number of different welding processes (e.g., FCAW-S, FCAW-G,GTAW, SAW, or similar welding processes) that use a welding wire. Thewelding system 10 includes a welding power source 12, a welding wirefeeder 14, a gas supply system 16, and a welding torch 18. The weldingpower source 12 generally supplies power to the welding system 10 andmay be coupled to the welding wire feeder 14 via a cable bundle 20. Thewelding power source 12 may also be coupled to a workpiece 22 using alead cable 24 having a clamp 26. In the illustrated embodiment, thewelding wire feeder 14 is coupled to the welding torch 18 via a cablebundle 28 in order to supply consumable, tubular welding wire (e.g., thewelding electrode) and power to the welding torch 18 during operation ofthe welding system 10. In another embodiment, the welding power source12 may couple and directly supply power to the welding torch 18.

The welding power source 12 may generally include power conversioncircuitry that receives input power from an alternating current powersource 30 (e.g., an AC power grid, an engine/generator set, or acombination thereof), conditions the input power, and provides DC or ACoutput power via the cable 20. As such, the welding power source 12 maypower the welding wire feeder 14 that, in turn, powers the welding torch18, in accordance with demands of the welding system 10. The lead cable24 terminating in the clamp 26 couples the welding power source 12 tothe workpiece 22 to close the circuit between the welding power source12, the workpiece 22, and the welding torch 18. The welding power source12 may include circuit elements (e.g., transformers, rectifiers,switches, and so forth) capable of converting the AC input power to adirect current electrode positive (DCEP) output, direct currentelectrode negative (DCEN) output, DC variable polarity, pulsed DC, or avariable balance (e.g., balanced or unbalanced) AC output, as dictatedby the demands of the welding system 10. It should be appreciated thatthe presently disclosed tubular welding wire may enable improvements tothe welding process (e.g., improved arc stability and/or improved weldquality) for a number of different power configurations.

The illustrated welding system 10 includes a gas supply system 16 thatsupplies a shielding gas or shielding gas mixtures from one or moreshielding gas sources 17 to the welding torch 18. In the depictedembodiment, the gas supply system 16 is directly coupled to the weldingtorch 18 via a gas conduit 32. In another embodiment, the gas supplysystem 16 may instead be coupled to the wire feeder 14, and the wirefeeder 14 may regulate the flow of gas from the gas supply system 16 tothe welding torch 18. In other embodiments, such as certain FCAW-S andSAW systems that do not rely on an externally supplied shielding gas,the welding system 10 may not include the gas supply system 16. Ashielding gas, as used herein, may refer to any gas or mixture of gases(e.g., inert or active gasses) that may be provided to the arc and/orweld pool in order to provide a particular local atmosphere (e.g., toshield the arc, improve arc stability, limit the formation of metaloxides, improve wetting of the metal surfaces, alter the chemistry ofthe weld deposit, and so forth).

In certain embodiments, the shielding gas flow may be a shielding gas orshielding gas mixture (e.g., argon (Ar), helium (He), carbon dioxide(CO₂), oxygen (O₂), nitrogen (N₂), hydrogen (H₂), similar suitableshielding gases, or any mixtures thereof). For example, a shielding gasflow (e.g., delivered via the gas conduit 32) may include Ar, CO₂,Ar/CO₂ mixtures (e.g., 75% Ar and 25% CO₂, 90% Ar and 10% CO₂, and soforth), Ar/CO₂/O₂ mixtures, Ar/He mixtures, and so forth. Further, itmay be appreciated that, as set forth in detail below, certain shieldinggases (e.g., certain Ar/CO₂ mixtures, such as 90% Ar/10% CO₂) may reducea total amount of welding fumes that may be generated during the weldingoperation.

Accordingly, the illustrated welding torch 18 generally receives thetubular welding wire from the welding wire feeder 14, power from thewelding power source 12, and a shielding gas flow from the gas supplysystem 16 in order to perform GMAW of the workpiece 22. Duringoperation, the welding torch 18 may be brought near the workpiece 22 sothat an arc 34 may be formed between the consumable welding electrode(i.e., the welding wire exiting a contact tip of the welding torch 18)and the workpiece 22. Additionally, as discussed below, by controllingthe composition of the tubular welding wire, the chemical and mechanicalproperties of the resulting weld may be varied. For example, the tubularwelding wire may include a deoxidizing component to react with andremove undesired species (e.g., oxygen, metal oxides, or other undesiredoxygen species) from the weld environment. In certain embodiments, thetubular welding wire may further include alloying components tocontribute species (e.g., copper, molybdenum, silicon, carbon, or othersuitable alloying components) to the weld pool, affecting the mechanicalproperties (e.g., strength and toughness) of the weld. Furthermore,certain components of the tubular welding wire may also provideadditional shielding atmosphere near the arc 34, affect the transferproperties of the arc 34, clean the surface of the workpiece 22, and soforth.

A cross-section of an embodiment of the presently disclosed welding wireis illustrated in FIG. 2. FIG. 2 illustrates a tubular welding wire 50having a metallic sheath 52 that encapsulates a granular or powderedcore 54, which may also be referred to as filler. The metallic sheath 52may be manufactured from any suitable metal or alloy (e.g., low-carbonsteel, low-alloy steel, or other suitable metal or alloy). In certainembodiments, the metal sheath 52 may provide approximately 70% toapproximately 90% of the total weight of the tubular welding wire 50.The metallic sheath 52 may include additives or impurities (e.g., ironoxides, carbon, manganese, silicon, nickel, or similar compounds orelements) that may be selected to provide desired properties for thetubular welding wire 50 as well as the weld bead. For example, certainembodiments of the tubular welding wire 50 may include a metallic sheath52 having less than approximately 0.02% carbon by weight. In otherembodiments, the metallic sheath 52 may include between approximately0.02% and approximately 0.16% carbon by weight.

Furthermore, in certain embodiments, the metallic sheath 52 of thetubular welding wire 50 may include relatively low manganese content. Incertain embodiments, the amount of manganese that may be present in themetallic sheath 52 may be between approximately 0.01% and approximately0.5% by weight (e.g., approximately 0.35% by weight or approximately0.26% by weight), while the granular core 54 may be completely free orsubstantially free from manganese (e.g., including little or no metallicmanganese and/or including little or no manganese compounds). Forexample, in certain embodiments, the granular core 54 may include lessthan 0.1%, less than 0.05%, less than 0.04%, less than 0.03%, less than0.02%, less than 0.01%, or approximately 0% (e.g., none or only traceimpurity quantities) manganese by weight. As such, a number of thepresently disclosed tubular welding wire embodiments have a manganesecontent (e.g., manganese metal or alloys, or manganese compounds, orboth) less than approximately 0.35% or less than approximately 0.4% byweight. Further, in certain embodiments, the metallic sheath 52 may becompletely free or substantially free (e.g., none or only trace impurityquantities) from manganese alloys, which may provide a tubular weldingwire 50 that is completely free or substantially free of manganesemetals and/or manganese compounds (e.g., manganese oxide).

The granular core 54 of the illustrated tubular welding wire 50 maygenerally be a compacted powder with a composition that, as discussedbelow, includes various components that each may serve at least one roleas an alloying component, arc stabilizer, slag forming component,deoxidizer, and/or filler during the welding process. These componentsof the granular core 54 may be homogenously or non-homogenously (e.g.,in clumps or clusters 56) disposed within the granular core 54. Incertain embodiments, the granular core 54 may provide betweenapproximately 10% and approximately 30% of the total weight of thetubular welding wire 50. Furthermore, as discussed in detail below, incertain embodiments, one or more components (e.g., certain arcstabilizing and/or slag forming components) may be prepared and includedin the granular core 54 as agglomerates (e.g., sintered and/or formedinto frits). It should be noted that the term “agglomerate” or “frit,”as used herein, refers to a mixture of compounds that have been fired orheated in a calciner or oven such that the components of the mixture arein intimate contact with one another. It should be appreciated that theagglomerate or frit may have subtly or substantially different chemicaland/or physical properties than the individual components of the mixtureused to form the agglomerate. For example, an agglomerate may generallybe better suited for the weld environment (e.g., drier and/or betterpowder flow) than a non-agglomerated form of the same component.

Tables 1, 2, and 3 are set forth below for various embodiments of thetubular welding wire 50. More specifically, Table 1 includes anon-limiting list of twelve example formulations (e.g., E1-E12) for thegranular core 54 for the presently disclosed tubular welding wire 50.Table 2 includes computed chemical composition for each of the exampleformulations (E1-E12) of the granular core 54 based on the componentsset forth in Table 1. Furthermore, Table 3 includes chemical andmechanical analysis results for weld deposits formed using each of thewelding wire embodiments set forth in Table 1. The welding wireembodiments E1-E12 may correspond to one or more AWS standards forwelding wire. That is, E1 may correspond to AWS A5.20 E71T-1C; E2 maycorrespond to AWS A5.20 E71T-1M; E3 and E9 may correspond to AWS A5.29E71T1-Ni1C (G); E4 and E10 may correspond to AWS A5.29 E71T1-Ni1M (G);E5 may correspond to AWS A5.29 E81T1-NiC; E6 may correspond to AWS A5.29E81T1-Ni1M; E7 may correspond to AWS A5.29 E81T1-K2C (G); E8 maycorrespond to AWS A5.29 E81T1-K2M (G); and E11 and E12 may correspond toAWS A5.20 E71T-G H8.

For the embodiments E1-E8 of Table 1, the metallic sheath 52 may accountfor approximately 84% of the weight of the tubular welding wire 50,while the remaining approximately 16% of the weight of the tubularwelding wire may be contributed by the granular core 54. For embodimentsE9-E12 of Table 1, the metallic sheath 52 may account for approximately85% of the weight of the tubular welding wire 50, while the remainingapproximately 15% may be contributed by the granular core. Further, forthe embodiments E1-E8, the metallic sheath 52 may include approximately0.35% manganese, while embodiments E9-E12 may include a metallic sheathhaving approximately 0.26% manganese. It should be appreciated that,while each component in Table 1 may be listed as serving a particularpurpose (e.g., as an alloying agent, arc stabilizer, slag former,deoxidizer, or filler), each component may actually serve more than onerole in the welding process. That is, for example, TiO₂ provided to theweld environment by the agglomerated titanium dioxide and/or the rutilepowder may actually provide stability to the arc 34 in addition toaiding in slag formation. By further example, certain deoxidizingcomponents (e.g., aluminum, magnesium, and/or zirconium) may bindstrongly to oxygen, and sometimes nitrogen as well, from the weldingatmosphere and form at least a portion of the slag around the weld bead.Similarly, certain deoxidizing components may also bind strongly tosulfur, which may come from the workpiece or from the welding consumable(e.g., as an impurity in the metallic sheath 52 or components of thegranular core 54). As such, it should be appreciated that thesecomponents may be otherwise classified (e.g., as arc stabilizers, slagforming components, and/or deoxidizers) without altering the presentinvention.

TABLE 1 Example formulations for the granular core 54 for embodimentsE1-E12 of tubular welding wire 50. Values are in weight percent relativeto the total weight of the granular core 54. Role Component E1 E2 E3 E4E5 E6 E7 E8 E9 E10 E11 E12 Alloying Ferro-molybdenum metal powder 0.00.0 0.0 0.0 1.5 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Nickel powder 2.5 2.5 5.26.2 5.5 5.5 11.5 10.5 6.8 6.3 9.0 9.0 Copper powder 0.0 0.0 0.0 0.0 0.01.5 0.0 0.0 0.0 0.0 0.0 0.0 High carbon iron powder 10.0 2.0 0.0 2.0 9.09.0 10.0 7.5 2.0 3.7 0.0 0.0 Arc Stabilizing Iron oxides 0.0 3.5 0.0 7.00.0 3.5 0.0 3.5 0.0 7.5 7.5 4.1 Potassium fluorosilicate 1.1 0.0 1.1 0.01.1 0.0 1.1 0.0 1.1 0.0 0.0 0.0 Sodium titanate frit 9.0 11.0 9.0 11.09.0 11.0 9.0 11.0 9.6 11.7 0.0 0.0 Sodium titanate frit 0.0 0.0 0.0 0.00.0 0.0 0.0 0.0 0.0 0.0 11.7 0.0 (pigment grade TiO₂) Lithium oxideagglomerate 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 5.5 Slag FormingRutile powder 5.0 0.0 5.0 0.0 5.0 0.0 5.0 0.0 5.0 0.0 0.0 0.0 Manganousoxide powder 0.0 4.0 0.0 0.0 0.0 5.0 0.0 4.0 0.0 0.0 0.0 0.0Agglomerated titanium dioxide 42.3 43.0 42.3 43.0 42.3 43.0 42.3 43.045.1 45.8 45.7 55.3 Deoxidizing Magnesium powder 0.5 0.0 0.5 0.0 0.5 0.00.5 0.0 0.9 0.0 0.0 0.0 Aluminum-zirconium metal 0.5 0.0 0.5 0.0 0.0 0.00.0 0.0 1.0 0.0 1.1 1.1 powder Ferro-zirconium-silicon powder 8.7 4.58.7 4.5 9.3 4.5 9.3 4.5 8.3 5.3 3.1 3.1 Aluminum-magnesium metal 3.8 4.33.8 4.3 3.7 4.3 3.7 4.3 3.3 4.3 3.7 3.7 powder Aluminum powder 0.0 0.60.0 0.6 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Ferro-silicon metal powder 0.04.7 0.0 4.7 0.0 6.0 0.0 4.7 0.0 4.1 0.0 0.0 Calcium silicon powder 0.00.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 3.5 3.5 Filling iron powder 16.619.9 23.9 16.7 13.1 6.7 7.6 7.0 16.9 11.3 14.7 14.7

TABLE 2 Computed chemical composition for each of the exampleformulations (E1-E12) of the granular core 54 based on the componentsset forth in Table 1. Values are in weight percent relative to the totalweight of the granular core 54. Further, the list is not exhaustive and,as such, the amounts of each constituent may not sum up to unity.Chemical name E1 E2 E3 E4 E5 E6 E7 E8 E9 E10 E11 E12 Aluminum (Al) 2.132.77 2.13 2.76 1.85 2.18 1.85 2.17 2.11 2.16 2.42 2.42 Carbon (C) 0.430.11 0.06 0.11 0.39 0.36 0.43 0.31 0.13 0.17 0.06 0.06 Copper (Cu) 0.000.00 0.00 0.00 0.00 1.50 0.00 0.00 0.00 0.00 0.00 0.00 Iron (Fe) 27.0424.91 24.76 21.46 23.22 19.14 18.14 17.29 19.63 17.46 15.20 15.20Magnesium (Mg) 2.40 2.15 2.40 2.15 2.35 2.16 2.35 2.16 2.54 2.14 1.841.84 Manganese (Mn) 0.03 0.00 0.00 0.01 0.03 0.00 0.04 0.00 0.01 0.010.00 0.00 Molybdenum (Mo) 0.00 0.00 0.00 0.00 0.94 0.00 0.00 0.00 0.000.00 0.00 0.00 Nickel (Ni) 2.49 2.50 5.18 6.17 5.48 5.51 11.46 10.516.77 6.27 8.96 8.96 Silicon (Si) 4.46 4.60 4.44 4.58 4.76 5.26 4.76 4.614.23 4.70 3.65 3.65 Zirconium (Zr) 3.62 1.73 3.62 1.73 3.57 1.74 3.571.73 3.73 2.04 1.78 1.78 Ferrous/ferric oxide (Fe_(x)O_(y)) 0.00 3.520.00 7.00 0.00 3.52 0.00 3.52 0.00 7.50 7.50 7.49 Maganous oxide (MnO)0.00 3.30 0.00 0.00 0.00 4.13 0.00 3.30 0.00 0.00 0.00 0.00 Potassiumoxide (K₂O) 0.36 0.36 0.36 0.36 0.36 0.36 0.36 0.36 0.38 0.38 0.38 0.46Sodium oxide (Na₂O) 1.55 1.81 1.55 1.79 1.55 1.81 1.55 1.80 1.65 1.911.91 0.65 Silicon dioxide (SiO₂) 2.80 3.07 2.80 2.95 2.80 3.11 2.80 3.072.98 3.14 3.13 4.06 Titanium dioxide (TiO₂) 50.81 48.32 50.81 48.1150.81 48.38 50.81 48.35 53.78 51.20 51.11 50.16 Lithium fluoride (LiF)0.81 0.82 0.81 0.82 0.81 0.82 0.81 0.82 0.86 0.87 0.87 1.05 Potassiumfluorosilicate (K₂SiF₆) 1.10 0.00 1.10 0.00 1.10 0.00 1.10 0.00 1.100.00 0.00 0.00 Calcium 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.001.01 1.01 Lithium oxide 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.000.00 0.00 1.03

As set forth in Table 1, in certain embodiments, the granular core 54 ofthe tubular welding wire 50 may include between approximately 4% andapproximately 18% alloying components by weight. For example, certainembodiments of the tubular welding wire 50 may include a granular core54 having ferro-molybdenum metal powder, nickel powder, copper powder,and/or high-carbon (e.g., between approximately 3.2% and 3.9% carbon byweight) iron powder. As set forth in Table 2, certain embodiments of thetubular welding wire 50 may include a granular core 54 having betweenapproximately 0% and approximately 1.5% copper, between approximately 2%and approximately 12% nickel, between approximately 0% and approximately1% molybdenum, and/or between approximately 0% and approximately 1%carbon by weight. While these alloying components may otherwisecontribute to the welding process (e.g., as arc stabilizers, slagformers, and/or deoxidizers), generally speaking, these alloyingcomponents are substantially incorporated (e.g., greater than 90%incorporated) into the weld metal to affect the properties (e.g.,strength, ductility, corrosion resistance, and so forth) of the weldbead and the surrounding workpiece 22.

Furthermore, as set forth in Table 1, in certain embodiments, thegranular core 54 of the tubular welding wire 50 may include betweenapproximately 10% and approximately 15% arc stabilizing components byweight. For example, certain embodiments of the tubular welding wire 50may include a granular core 54 having iron oxides, potassiumfluorosilicate, sodium titanate frit (e.g., made using either rutile orpigment-grade TiO₂), and/or lithium oxide agglomerate. As set forth inTable 2, certain embodiments of the tubular welding wire 50 may includea granular core 54 having between approximately 0% and 7.5% iron oxides,between approximately 0% and 2% potassium fluorosilicate, betweenapproximately 0% and approximately 12% sodium titanate frit, and between0% and 6% lithium oxide agglomerate by weight. Again, while thesecomponents may otherwise contribute to the welding process (e.g., asslag formers and/or deoxidizers), these arc stabilizers may generallyprovide species to the arc that readily ionize, enabling a moreconsistent and/or controllable arc 34 to the surface of the workpiece22. The presently disclosed sodium titanate frit may be a sinteredmixture of sodium titanate and lithium fluoride and/or sodium silicatethat may be better suited for the weld environment (e.g., drier and/orbetter powder flow) than non-agglomerated sodium titanate. As indicatedin Table 1, in certain embodiments, the sodium titanate may be made fromrutile and, accordingly, may have one or more of the aforementionedimpurities that rutile may commonly include. In other embodimentsindicated in Table 1, the sodium titanate may instead be made frompigment grade TiO₂, which may lack one or more of these impurities. Byspecific example, an embodiment of a pigment-grade sodium titanate fritmay include approximately 11.8% sodium oxide, approximately 5.7% silica,and approximately 82.5% pigment-grade TiO₂. Similarly, as indicated inTable 1, certain embodiments may include a lithium agglomerate that maybe a sintered mixture of lithium oxide, iron oxides, sodium oxide, andsilica, which may be better suited for the weld environment (e.g., drierand/or better powder flow) than a non-agglomerated mixture of thesecomponents. By specific example, in certain embodiments, the lithiumagglomerate may include approximately 18.7% lithium oxide, approximately61.6% iron oxides, approximately 0.2% sodium oxide, and approximately19.5% silica.

Additionally, as set forth in Table 1, in certain embodiments, thegranular core 54 of the tubular welding wire 50 may include betweenapproximately 40% and approximately 50% slag forming components byweight. Certain embodiments of the tubular welding wire 50 may include agranular core 54 having rutile powder, manganous oxide powder, and/oragglomerated titanium dioxide. For example, certain embodiments of thepresently disclosed welding wire 50 may have a granular core 54 thatincludes between approximately 3% and approximately 5% manganese oxidepowder by weight. Other embodiments of the presently disclosed weldingwire 50 may have a granular core 54 that includes substantially no(e.g., approximately 0%) manganese oxide powder by weight. Accordingly,as set forth in Table 2, in certain embodiments, this may result ingranular cores 54 and/or tubular welding wires 50 having a manganesecontent (e.g., as a metal and/or as a component of a chemical compound)less than approximately 3.5%, 3%, 2.5%, 2%, 1%, 0.5%, 0.35%, 0.05%,0.03%, 0.01%, or even 0.001% by weight.

In terms of other slag forming components, in certain embodiments, thegranular core 54 of the tubular welding wire 50 may include betweenapproximately 45% and approximately 55% titanium dioxide by weight(e.g., from the rutile and/or agglomerated titanium dioxide sources).Accordingly, in certain embodiments, the tubular welding wire 50 mayinclude between approximately 6% and approximately 8% pigment-grade TiO₂by weight. It should be appreciated that, the TiO₂ used to form thepresently disclosed agglomerated titanium dioxide is a pigment-gradeTiO₂ (e.g., greater than 95%, 99%, 99.9%, or 99.99% TiO₂) that may lackor have lower levels of one or more impurities typically found in rutile(e.g., iron, niobium, tantalum, vanadium, and/or other impurities). Thatis, pigment grade TiO₂ is generally both purified and milled, incontrast to lower purity TiO₂, such as milled rutile.

Furthermore, in certain embodiments, this pigment-grade TiO₂ may besintered with one or more drying and/or binding agents (e.g., lithiumfluoride, and/or sodium silicate) to form the agglomerated titaniumdioxide component of the granular core 54. For example, in certainembodiments of the presently disclosed welding wire 50, an agglomeratedtitanium dioxide component may be formed by dry mixing purified TiO₂powder and purified (e.g., precipitated grade) lithium fluoride for aperiod of time (e.g., 10 min). Then, as mixing continues, a concentratedaqueous solution of sodium silicate and a concentrated aqueous solutionof potassium silicate may be slowly added to the dry mixture along with,in certain situations, a small quantity of water until a desiredconsistency is achieved (e.g., mixture begins to “ball”). After mixingfor an additional period of time (e.g., 3 to 5 min), in certainembodiments, the wet mixture may be disposed in an oven (e.g., a directfired kiln) and heated to approximately 1200° F. to approximately 1600°F. for approximately 15 to 25 minutes (or heated to similar temperaturesin a pan for approximately 2 hours). In certain embodiments, the TiO₂agglomerate may be made from approximately 81.3% purified TiO₂,approximately 11% sodium silicate, approximately 6% potassium silicate,and approximately 1.7% lithium fluoride. Once the agglomerate has beenformed (e.g., after firing), in certain embodiments, the agglomerate mayconsist of pigment-grade TiO₂, silica, potassium oxide, sodium oxide andlithium fluoride (e.g., approximately 90.7% TiO₂, approximately 5.4%silica, approximately 1.2% sodium oxide, approximately 0.8% potassiumoxide, and approximately 1.9% lithium fluoride). While not desiring tobe bound by theory, it is believed that using a combination of bothsodium and potassium silicates, as presently disclosed, provides a TiO₂agglomerate that may be especially resistant to accumulating moisturefrom the surrounding environment. Additionally, in certain embodiments,using lithium fluoride in combination with these two silicates increasesthe moisture resistance of the TiO₂ agglomerate and enables theformation of a harder and/or denser TiO₂ agglomerate.

Additionally, as set forth in Table 1, in certain embodiments, thegranular core 54 of the tubular welding wire 50 may include betweenapproximately 10% and approximately 15% deoxidizers by weight. Forexample, certain embodiments of the tubular welding wire 50 may includea granular core 54 having magnesium powder, aluminum-zirconium metalpowder, ferro-zirconium-silicon powder, aluminum-magnesium metal powder,aluminum powder, ferro-silicon metal powder, and/or calcium siliconpowder. By specific example, certain embodiments of tubular welding wire50 may have a granular core 54 that includes aluminum-zirconium metalpowder and/or ferro-zirconium-silicon powder as deoxidizing components.In certain embodiments, the calcium silicon powder may includeapproximately 30% calcium, approximately 60% silicon, approximately 6%iron, and approximately 1% carbon by weight of the powder. In certainembodiments, as set forth in Table 2, the granular core 54 of thetubular welding wire 50 may include between approximately 0% andapproximately 3% aluminum, between approximately 0% and approximately 3%magnesium, between approximately 0% and approximately 4% zirconium,and/or between approximately 0% and approximately 6% silicon by weight.While these components may otherwise contribute to the welding process(e.g., as arc stabilizers or slag formers), these deoxidizing componentsare generally selected to strongly bind oxygen in order to block (e.g.,limit or prevent) this oxygen from remaining in the weld pool andweakening the weld deposit.

Furthermore, as set forth in Table 1, in certain embodiments, thegranular core 54 of the tubular welding wire 50 may include betweenapproximately 5% and approximately 25% filler metal by weight. Forexample, certain embodiments of the tubular welding wire 50 may includea granular core 54 having iron powder as the filler metal. As set forthin Table 2, certain embodiments of the tubular welding wire 50 may havea granular core 54 including between approximately 15% and approximately30% iron by weight. While the iron powder may otherwise contribute tothe welding process (e.g., as an arc stabilizer, slag former, and/ordeoxidizer), the iron powder may generally provide a substantial portionof the metal used to form the weld on the workpiece 22. As such, most ofthe iron powder included in the granular core 54 may be incorporatedinto and form the weld deposit.

Table 3 includes chemical and mechanical analysis results for welddeposits formed using the welding wire embodiments (e.g., embodimentsE1-E12) set forth in Tables 1 and 2. It should be noted that theelements included in Table 3 include values in the form of weightpercentages for a non-exhaustive list of elements; other elements (e.g.,Fe) and other trace impurities (e.g., arsenic (As)) may also be presentwithin the weld metal. In general, it should be noted that all of thetubular welding wire embodiments provide weld deposits having relativelylow oxygen content (e.g., between approximately 0% and approximately0.15%, between approximately 0.05% and approximately 0.10%, or less thanapproximately 0.09% by weight) and relatively low nitrogen content(e.g., between approximately 0% and approximately 0.01%, betweenapproximately 0.004% and approximately 0.009%, or less than 0.01% byweight). Additionally, in certain embodiments of the tubular weldingwire 50, the use of the pigment grade TiO₂ in the agglomerated titaniumdioxide generally enables the formation of weld deposits havingrelatively low vanadium content (e.g., between approximately 0.006% andapproximately 0.008% or less than approximately 0.009% by weight) andrelatively low niobium content (e.g., between approximately 0.003% andapproximately 0.005% or less than approximately 0.006% by weight), whichmay offer advantages to the weld deposit. Furthermore, as set forth inTable 3, certain embodiments of the tubular welding wire 50 may formweld deposits having a manganese content between approximately 0.2% andapproximately 0.5%, between approximately 0.25% and approximately 0.4%,or between approximately 0.3% and approximately 0.4% by weight. Incontrast, other T-1 welding wires (e.g., AWS A5.20 EXXT-1, A5.29EXXT1-YY, A5.36 EXXT-1, and EXXT1-YY) may form weld deposits havinggreater than approximately 0.75% manganese by weight, while typicalself-shielded welding wires may generally form weld deposits havinggreater than approximately 0.5% manganese. Accordingly, the presentlydisclosed tubular welding wires 50 enable the formation of weld depositshaving substantially lower manganese content (e.g., less than 0.5%, suchas 0.15% or even 0.05% manganese by weight) than weld deposits fromother welding wires, while still maintaining good weld properties.

Table 3 also lists mechanical properties for each of the example welddeposits formed using the welding wire embodiments (e.g., embodimentsE1-E12) listed in Table 1. Specifically, Table 3 includes mechanicalproperty measurements for yield strength, tensile strength, percentelongation, and Charpy-V-Notch (CVN) values at −20° F. and −40° F. asdetermined based on AWS A5.20 (e.g., E71T1-GM), A5.36, or anothersuitable standard. In general, the example weld deposits may demonstrateyield strengths from approximately 60 ksi to approximately 75 ksi,tensile strengths from approximately 70 ksi to approximately 85 ksi,percent elongation from approximately 20% to approximately 35%, CVN fromapproximately 40 ft-lbs to approximately 105 ft-lbs at −20° F., and CVNfrom approximately 35 ft-lbs to approximately 95 ft-lbs at −40° F. Forexample, in certain embodiments, the weld deposit demonstrated a CVN ofgreater than 65 ft-lbs, greater than 70 ft-lbs, greater than 75 ft-lbs,greater than 80 ft-lbs, greater than 85 ft-lbs, greater than 90 ft-lbs,or greater than 100 ft-lbs at −20° F. By further example, in certainembodiments, the weld deposit demonstrated a CVN of greater than 45ft-lbs, greater than 50 ft-lbs, greater than 70 ft-lbs, greater than 75ft-lbs, greater than 80 ft-lbs, greater than 85 ft-lbs, or greater than90 ft-lbs at −40° F. Further, for embodiments E11 and E12, the CVN at−60° F. is approximately 100 ft-lbs as listed in Table 3. It should benoted that despite the relatively low manganese content determined forthe weld deposits E1-E12 (e.g., less than approximately 0.5%), the welddeposits possess relatively high toughness and a suitable tensilestrength for the classification type, as compared to conventionalwelding wires.

TABLE 3 Example elemental analyses and mechanical test results for welddeposits E1-E12 formed using the corresponding tubular welding wireembodiments E1-E12 of Table 1. Elemental values are in weight percentrelative to the total weight of the weld deposit. Weld deposits wereformed using the following parameters: Amps: 260; Volts: 26-28; DCEP;Wire Feed Speed: 450 inches per minute; Electrical Stickout: 0.75 in.;Travel Speed: 10 inches per minute; Angle: 45°; Position: 1g; ShieldingGas: 100% CO₂, 75% Argon and 25% CO₂, or 90% Argon and 10% CO₂. N/Adenotes measurements that are not presently available. E1 E2 E3 E4 E5 E6E7 E8 E9 E10 E11/12 Element Carbon (C) 0.067 0.032 0.020 0.028 0.0750.077 0.071 0.058 0.035 0.080 0.027 Manganese (Mn) 0.205 0.388 0.2060.206 0.222 0.429 0.229 0.392 0.251 0.217 0.245 Phosphorus (P) 0.0080.010 0.008 0.006 0.011 0.010 0.009 0.013 0.009 0.012 0.011 Sulfur (S)0.008 0.008 0.008 0.008 0.010 0.010 0.008 0.011 0.008 0.013 0.008Silicon (Si) 0.366 0.496 0.427 0.486 0.524 0.607 0.451 0.485 0.488 0.4780.385 Copper (Cu) 0.045 0.047 0.047 0.045 0.050 0.282 0.042 0.048 0.0180.014 0.016 Chromium (Cr) 0.047 0.034 0.048 0.033 0.058 0.033 0.0770.047 0.026 0.034 0.019 Vanadium (V) 0.007 0.007 0.008 0.006 0.008 0.0070.008 0.006 0.007 0.008 0.003 Nickel (Ni) 0.448 0.467 0.927 1.096 1.0570.978 2.084 2.044 1.070 1.028 1.410 Molybdenum (Mo) 0.007 0.009 0.0070.006 0.171 0.006 0.008 0.007 0.005 0.006 0.002 Aluminum (Al) 0.0130.022 0.015 0.034 0.012 0.017 0.016 0.014 0.016 0.014 0.021 Titanium(Ti) 0.061 0.053 0.062 0.059 0.061 0.064 0.069 0.054 0.085 0.050 0.060Niobium (Nb) 0.003 0.004 0.005 0.003 0.005 0.005 0.005 0.005 0.006 0.0050.003 Cobalt (Co) 0.002 0.004 0.003 0.002 0.004 0.004 0.004 0.008 0.0030.004 0.003 Tungsten (W) 0.005 0.005 0.005 0.005 0.005 0.005 0.005 0.0120.005 0.008 0.005 Tin (Sn) 0.005 0.004 0.004 0.002 0.003 0.001 0.0050.003 0.002 0.001 0.005 Zirconium (Zr) 0.008 0.005 0.009 0.007 0.0080.004 0.009 0.004 0.011 0.008 0.010 Antimony (Sb) 0.000 0.001 0.0000.000 0.003 0.001 0.000 0.005 0.000 0.001 0.000 Oxygen (O) 0.077 0.0750.073 0.080 N/A N/A 0.067 0.065 0.070 0.078 0.079 Nitrogen (N) 0.0050.004 0.004 0.009 N/A N/A 0.004 0.004 0.005 0.004 0.005 Property YieldStrength (KSI) 64.2 61.2 62.9 65.1 70.8 71.5 71.6 70.1 66.9 63.2 63.8Tensile Strength (KSI) 74.1 71.4 70.9 72.8 83.4 82.2 83.6 81.9 74.8 72.872.1 % Elongation 27.2 30.5 29.2 28 26.8 25.8 23.1 26.8 28.2 28.7 30.2CVN (ft-lbs) @ −20° F. 85 87 101 70 41 66 77 76 96 85 101 CVN (ft-lbs) @−40° F. 52 45 93 75 49 51 69 65 63 45 N/A CVN (ft-lbs) @ −60° F. N/A N/AN/A N/A N/A N/A N/A N/A N/A N/A 100

FIG. 3 illustrates an embodiment of a process 60 by which a workpiece 22may be welded using the disclosed welding system 10 and tubular weldingwire 50. The illustrated process 60 begins with feeding (block 62) thetubular welding electrode 50 (i.e., the tubular welding wire 50) to awelding apparatus (e.g., welding torch 18). Additionally, the process 60includes providing (block 64) a shielding gas flow (e.g., 100% argon,100% CO₂, 75% argon/25% CO₂, 90% argon/10% CO₂, or similar shielding gasflow) near the contact tip of the welding apparatus (e.g., the contacttip of the torch 18). In other embodiments, welding systems may be usedthat do not use a gas supply system (e.g., such as the gas supply system16 illustrated in FIG. 1) and one or more components (e.g., potassiumcarbonate) of the tubular welding electrode 50 may decompose to providea shielding gas component (e.g., carbon dioxide).

Continuing through the process 60, next, the tubular welding electrode50 may be brought near (block 66) the workpiece 22 to strike and sustainan arc 34 between the tubular welding wire 50 and the workpiece 22. Itshould be appreciated that the arc 34 may be produced using, forexample, a DCEP, DCEN, DC variable polarity, pulsed DC, balanced orunbalanced AC power configuration for the GMAW system 10. Once the arc34 has been established to the workpiece 22, a portion of the tubularwelding electrode 50 (e.g., filler metals and alloying components) maybe transferred (block 68) into the weld pool on the surface of theworkpiece 22 to form a weld bead of a weld deposit. Meanwhile, theremainder of the components of the tubular welding electrode 50 may bereleased (block 70) from the tubular welding electrode 50 to serve asarc stabilizers, slag formers, and/or deoxidizers to control theelectrical characteristics of the arc and the resulting chemical andmechanical properties of the weld deposit.

As set forth above, the presently disclosed welding system 10 mayprovide low fume generation rates (FGR) and/or low manganese fumegeneration rates (MnFGR). That is, the presently disclosed tubularwelding wire 50 (e.g., working in combination with particular shieldinggases) may provide low FGRs and/or low MnFGRs. Table 4 includes FGR andMnFGR data for a number of standard welding electrodes alongside FGR andMnFGR data for the disclosed welding electrode embodiments E1-E12.Accordingly, as illustrated in Table 4, certain disclosed welding wireembodiments may afford a FGR of less than 0.8 grams per min (g/min),less than 0.7 g/min, less than 0.6 g/min, less than 0.5 g/min, less than0.4 g/min, less than 0.35 g/min, or less than 0.34 g/min. Furthermore,as illustrated in Table 4, certain disclosed welding wire embodimentsmay afford a MnFGR of less than 0.06 g/min, less than 0.05 g/min, lessthan 0.04 g/min, less than 0.03 g/min, less than 0.02 g/min, less than0.01 g/min, less than 0.009 g/min, less than 0.008 g/min, or less than0.007 g/min.

For further comparison, AWS F3.2 Annex B indicates that a typical FGRproduced by an E71T-1 FCAW electrode is approximately 0.7 g/min to 0.8g/min; while the FGRs of certain presently disclosed welding wireembodiments listed in Table 4 are between approximately 0.3 g/min and0.6 g/min, especially for certain shielding gases (e.g., argon/CO₂mixtures). Additionally, AWS F3.2 Annex C indicates that the typicalmanganese contribution to the total fumes produced by an E70T-1 FCAWelectrode is between 6.2% and 13.5%, and AWS F3.2 Annex D indicates thatE70T-1 and E71T-1 FCAW electrodes typically produce total fumes having8.1% or 9.0% manganese. In contrast, the MnFGRs presented in Table 4represent approximately 1.1% to approximately 3.3% manganesecontribution to the total fume, significantly lower than other weldingelectrodes. As such, the presently disclosed welding wires embodimentsE1-E12 provide low FGRs as well as low MnFGRs.

TABLE 4 Fume generation rates (FGR) and manganese fume generation rate(MnFGR) in grams per min (g/min) for standard welding wires anddisclosed welding wire embodiments (E1-E10) using the indicatedshielding gas, amperage, and voltage (DCEP). Testing was performedaccording to AWS F1.2:2006 using 0.045″ diameter wire and a melt rate ofapproximately 7 lbs/hour (approximately 53-54 g/min). 200 A/27.0 V 225A/27.5 V 250 A/28.0 V 275 A/28.5 V 300 A/29.0 V Welding Wire FGR MnFGRFGR MnFGR FGR MnFGR FGR MnFGR FGR MnFGR AWS A5.20: E71T-1C (100% CO₂)0.4307 0.0383 0.4813 0.0361 0.5861 0.0416 0.6725 0.0437 0.6508 0.0397 E1(100% CO₂) 0.5945 0.0083 0.7229 0.0101 0.7523 0.0120 0.8237 0.01320.8663 0.0182 E3; E9 (100% CO₂) 0.4742 0.0066 0.4648 0.0060 0.63680.0089 0.7615 0.0114 0.7111 0.0128 AWS A5.20: E71T-1M 0.3978 0.03020.4406 0.0286 0.6064 0.0388 0.6401 0.0512 0.4917 0.0339 (75% Ar/25% CO₂)E2 (75% Ar/25% CO₂) 0.4267 0.0154 0.4687 0.0150 0.5812 0.0174 0.60950.0171 0.4440 0.0147 E4; E10 (75% Ar/25% CO₂) 0.3337 0.0043 0.40920.0045 0.5710 0.0074 0.6125 0.0086 0.4565 0.0082 AWS A5.29: E81T1-K2CJH8 0.4861 0.0262 0.5741 0.0350 0.7507 0.0435 0.8830 0.0512 0.8172 0.0482(100% CO₂) AWS A5.29: E81T1-K2MJ H8 0.5482 0.0378 0.6300 0.0365 0.79950.0416 0.9925 0.0466 0.8541 0.0512 (100% CO₂) E7 (100% CO₂) 0.56390.0085 0.6070 0.0079 0.8214 0.0131 0.8653 0.0130 0.8080 0.0145 AWSA5.29: 81T1-K2MJ H8 0.4721 0.0321 0.5644 0.0316 0.7245 0.0464 0.86000.0447 0.7029 0.0422 (75% Ar/25% CO₂) E8 (75% Ar/25% CO₂) 0.4050 0.01220.4147 0.0116 0.5385 0.0172 0.6105 0.0165 0.5579 0.0162

Table 5 further illustrates an effect of the shielding gas on the FGRfor the disclosed welding electrodes. In particular, Table 5 illustratesFGR for a standard welding wire in comparison to disclosed welding wireembodiments E10, E11, and E12 using different shielding gas mixtures. Asindicated in Table 5, a standard welding electrode (e.g., a standardE71T-1C electrode) may have a FGR of approximately 0.61 g/min, resultingin approximately 0.7% of the electrode being converted to fumes. Bymoving to the disclosed welding electrode E10 under the same shieldinggas conditions, the FGR may be reduced to approximately 0.58 g/min.Additionally, when using the disclosed welding electrode E11 and a 90%Ar/10% CO₂ shielding gas, the FGR may be reduced to approximately 0.40g/min (e.g., with approximately 0.5% of the electrode converted tofumes); and when using the disclosed welding electrode E12 and the 90%Ar/10% CO₂ shielding gas, the FGR may be reduced to approximately 0.34g/min (e.g., approximately 0.42% of the electrode converted to fumes).Further, certain embodiments of the presently disclosed tubular weldingwire 50 may generally enable high melt rates (e.g., greater thanapproximately 53 g/min, greater than approximately 54 g/min, etc.) whilemaintaining the aforementioned low FGRs. As such, while other weldingwires may have FGRs greater than 0.5 g/min or greater than 0.6 g/min,which may correspond to a conversion of approximately 0.7% or more ofthe welding wire (by weight) into welding fumes, the presently disclosedwelding system may enable FGRs corresponding to a conversion of lessthan approximately 0.6%, less than 0.5%, or less than 0.45% of thewelding wire into fumes. Accordingly, Table 5 illustrates that certainembodiments of the presently disclosed welding system 10 may provideFGRs that are between approximately 30% and approximately 40% lower thanthe FGR of a standard (e.g., AWS A5.20: E71T1-1C) welding electrode withcertain shielding gases. Indeed, in certain embodiments, the disclosedwelding electrode embodiments may provide melt rates as high asapproximately 80 g/min while maintaining a fume generation rate ofapproximately 0.4 g/min (e.g., with approximately 0.5% of the electrodeconverted to fumes) or approximately 0.35 g/min (e.g., withapproximately 0.4% of the electrode converted to fumes) with theappropriate shielding gas (e.g., 90% Ar/10% CO₂).

TABLE 5 Fume generation rates (FGR) for a standard welding wire andwelding wire embodiments E10, E11, and E12 using the indicated shieldinggas, amperage, and voltage (DCEP). Testing was performed according toAWS F1.2:2006 using 0.045″ diameter wire. AWS A5.20: E71T-1C E10 E11 E12Amperage 250 250 250 250 Voltage 27 27 26 26 Shielding Gas 75% Ar/ 75%Ar/ 90% Ar/ 90% Ar/10% CO₂ 25% CO₂ 25% CO₂ 10% CO₂ FGR (g/min) 0.60640.5812 0.4043 0.3387 % Electrode 0.7 0.74 0.5 0.42 to Fumes Melt Rate53-54 53-54 80 80 (g/min) Melt Rate 7 7 10.6 10.6 (lbs/hour)

FIG. 4 illustrates an embodiment of a process 80 by which the tubularwelding wire 50 may be manufactured. It may be appreciated that theprocess 80 merely provides an example of manufacturing a tubular weldingwire 50; however, in other embodiments, other methods of manufacturingmay be used to produce the tubular welding wire 50 without spoiling theeffect of the present approach. That is, for example, in certainembodiments, the tubular welding wire 50 may be formed via aroll-forming method or via packing the core composition into a hollowmetallic sheath. The illustrated process 80 begins with a flat metalstrip being fed (block 82) through a number of dies that shape the stripinto a partially circular metal sheath 52 (e.g., producing a semicircleor trough). After the metal strip has been at least partially shapedinto the metal sheath 52, it may be filled (block 84) with the filler(i.e., the granular core 54), such as the formulations E1-E12 for thegranular core 54 filler discussed with respect to Table 1. That is, thepartially shaped metal sheath 52 may be filled with various powderedalloying, arc stabilizing, slag forming, deoxidizing, and/or fillingcomponents. In certain embodiments, the disclosed tubular welding wire50 may be completely free or substantially free of manganese or may be alow manganese (e.g., less than approximately 0.4% manganese by weight)welding wire. In other embodiments, the granular core 54 of the tubularwelding wire 50 may be completely free or substantially free ofmanganese, and only the metal sheath 52 includes (e.g., approximately0.35%, approximately 0.26%, or less) manganese.

Continuing through the process 80, once the components of the granularcore material 54 have been added to the partially shaped metal sheath52, the partially shaped metal sheath 52 may then be fed through (block86) one or more devices (e.g., drawing dies or other suitable closingdevices) that may generally close the metal sheath 52 such that itsubstantially surrounds the granular core material 54 (e.g., forming aseam 58). Additionally, the closed metal sheath 52 may subsequently befed through (block 88) a number of devices (e.g., drawing dies or othersuitable devices) to reduce the circumference of the tubular weldingwire 50 by compressing the granular core material 54.

While only certain features of the invention have been illustrated anddescribed herein, many modifications and changes will occur to thoseskilled in the art. It is, therefore, to be understood that the appendedclaims are intended to cover all such modifications and changes as fallwithin the true spirit of the invention.

1. A tubular welding wire, comprising: a sheath and a core, wherein thetubular welding wire comprises less than approximately 0.4% manganesemetal or alloy by weight, and wherein the tubular welding wire isconfigured to form a weld deposit comprising less than approximately0.5% manganese by weight.
 2. The tubular welding wire of claim 1,wherein the tubular welding wire comprises less than approximately 0.2%manganese metal or alloy by weight.
 3. The tubular welding wire of claim1, wherein the core is substantially free of manganese metal andcompounds of manganese.
 4. The tubular welding wire of claim 1, whereinthe core comprises agglomerated titanium dioxide, and wherein theagglomerated titanium dioxide includes a sintered mixture comprisingtitanium dioxide, silica, and sodium oxide.
 5. The tubular welding wireof claim 1, wherein the core comprises agglomerated titanium dioxide,and wherein the agglomerated titanium dioxide includes a sinteredmixture consisting essentially of pigment-grade titanium dioxide,silica, sodium oxide, potassium oxide, and lithium fluoride.
 6. Thetubular welding wire of claim 1, wherein titanium dioxide comprisesbetween approximately 35% and approximately 55% of the core by weight.7. The tubular welding wire of claim 1, wherein zirconium comprisesbetween approximately 0.15% and approximately 0.5% of the tubularwelding wire by weight.
 8. The tubular welding wire of claim 1, whereinthe weld deposit comprises approximately 0.15% manganese by weight.
 9. Amethod, comprising: forming a weld deposit on a workpiece using awelding electrode, wherein the weld deposit comprises less thanapproximately 0.5% manganese by weight, and wherein a Charpy V-Notch(CVN) toughness of the weld deposit is greater than approximately 65foot-pounds (ft-lbs) at −20° F. and greater than approximately 45 ft-lbsat −40° F.
 10. The method of claim 9, wherein the welding electrode isconfigured to provide a fume generation rate less than approximately 0.6g/min at a melt rate greater than or equal to 54 g/min.
 11. The methodof claim 10, wherein the welding electrode is configured to provide afume generation rate less than approximately 0.5 g/min at a melt rate ofgreater than or equal to 80 g/min.
 12. The method of claim 10, whereinthe welding electrode is configured to provide a manganese fumegeneration rate less than approximately 0.06 g/min at a melt rategreater than or equal to 54 g/min.
 13. The method of claim 12, whereinthe welding electrode is configured to provide a manganese fumegeneration rate less than approximately 0.02 g/min at a melt rategreater than or equal to 54 g/min.
 14. The method of claim 9, whereinthe weld deposit comprises between approximately 0.2% and approximately0.25% manganese by weight.
 15. The method of claim 9, wherein a yieldstrength of the weld deposit is greater than approximately 60 kilopoundsper square inch (KSI), and wherein a tensile strength of the welddeposit is greater than approximately 70 KSI, and wherein an elongationof the weld deposit is approximately 22%.
 16. The method of claim 9,wherein a yield strength of the weld deposit is greater thanapproximately 65 kilopounds per square inch (KSI), and wherein a tensilestrength of the weld deposit is greater than approximately 80 KSI, andwherein an elongation of the weld deposit is approximately 19%.
 17. Themethod of claim 9, wherein the CVN toughness of the weld deposit isgreater than approximately 70 ft-lbs at −20° F. and greater thanapproximately 50 ft-lbs at −40° F.
 18. The method of claim 9, whereinthe CVN toughness of the weld deposit is greater than approximately 80ft-lbs at −20° F. and greater than approximately 55 ft-lbs at −40° F.19. A method of manufacturing a welding electrode, comprising: formingan agglomerate by sintering a mixture comprising pigment-grade titaniumdioxide, potassium silicate, and sodium silicate, and lithium fluoride;mixing the agglomerate with at least one alloying component, at leastone arc stabilizing component, and at least one deoxidizing component toform a granular core; and disposing the granular core within a metallicsheath to form the welding electrode, wherein the welding electrodecomprises less than approximately 0.4% manganese metal or alloy byweight.
 20. The method of claim 19, wherein the core comprises less thanapproximately 15% deoxidizing components by weight, betweenapproximately 4% and approximately 18% alloying components by weight,between approximately 10% and approximately 15% arc stabilizingcomponents by weight, between approximately 40% and approximately 50%slag forming components by weight, and between approximately 6% andapproximately 24% filler metal by weight.